On Fri, 16 Jul 2004 10:36 am, Serguei.Patchkovskii at sympatico.ca wrote:
> Unless your code is very similar to one of the SPEC benchmarks, 8.0 may
> also generate slower code, compared to ifc 7.1, even though 8.0 presumably
> includes much better high-level optimizers.
Version 8.0 can create faster code for some real world programs (at a price),
this quote comes from the NAMD list:
[quote]
I just finished a compile of tcl, fftw, charm++ and namd all using the -xN
-O3 icc8.0 compiler flags.
Compared to the previous executable I get about a 13% gain in speed for
the same exact namd.config. I did notice that memory usage more than
doubled and this is troubling.
[/quote]
However, others are seeing some wierder problems, this quote is from the
mpiexec list:
[quote]
But when run with ./a.out <inp all seems well. The a.out exec was
compiled with the mpif90 command. I don't know who is at fault here,
the compiler or mpiexec. I have been told that old programs continue to
work, even with the newly compiled mpiexec, but once recompiled with the
v8 Intel compilers, all redirection breaks.
[/quote]
Pete W looked at the straces provided with and without mpiexec and saw:
[quote]
Note that the Intel compiler Fortran runtime library seems to be
statting stdin and finds a regular file in the "without" case, but
finds a socket in the "with" case. Nevertheless it tries to seek
backwards one byte for both, which is not a valid thing to do on
a socket.
....
If you want to abstract mpiexec out of this to complain to intel,
try something like this:
cat inp | rsh localhost strace -o $(pwd)/socket $(pwd)/a.out
I get S_IFSOCK and one-byte-at-a-time reads, but hopefully your
compiler will cause this to fail, just like in the mpiexec case.
[/quote]
--
Christopher Samuel - (03)9925 4751 - VPAC Systems & Network Admin
Victorian Partnership for Advanced Computing http://www.vpac.org/
Bldg 91, 110 Victoria Street, Carlton South, VIC 3053, Australia
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: signature
URL: <http://www.beowulf.org/pipermail/beowulf/attachments/20040716/14a170be/attachment.sig>